1. Field of the Art
The present invention relates to couplers for hitching trailing vehicles to towing vehicles, and more particularly, to latching mechanisms for securely latching couplers of trailing vehicles to a spherical ballhead of a towing vehicle.
2. Discussion of the Related Art
The ballhead coupler is a common type of coupling mechanism used to hitch a wide variety of trailers to towing vehicles--e.g., boat trailers, RV trailers, flat-bed trailers, cargo trailers, etc. The ballhead coupler is characterized by a coupling post having a spherical ballhead securely mounted to the rear bumper or frame of a towing vehicle. The mating coupler, provided on the nose or tongue of a trailer, has a corresponding downwardly opening socket that receives and captures the ballhead to achieve a pivotal connection therewith.
The ballhead coupler just described is popular, in part, because it offers tremendous performance advantages over other types of trailer couplers. Most notably, the spherical shape of the coupling allows both side-to-side and up-down pivotal movement between the trailer and towing vehicle, as encountered during turns or travel over bumps, with virtually no torque translated through the coupler to the towing vehicle. As a result, a smother ride and greater vehicle steering control are achieved.
In order to facilitate attachment of the trailer to the coupling post, the mouth of the downwardly opening receiving socket must be larger than the diameter of the ballhead. This allows the coupler to be readily lowered onto the ballhead. Without more, however, the trailer would tend to uncouple when traveling over bumps or rough roads. Therefore, some type of retaining mechanism is needed to lock the coupler with the ballhead secured within the socket of the coupler. It is appreciated, however, that the retaining mechanism must be designed to allow pivotal movement between the receiving socket and the coupling post and, thus, preserve the low torque connection between the trailer and towing vehicle.
Typically, a ball clamp of some type is provided to latch or captively engage the ballhead within the receiving socket of the trailer coupler, and yet maintain the pivotal connection therebetween. For example, U.S. Pat. No. 4,763,917 to Chambers, shows a lever-latch 30 that is manually operated to engage a ball clamp against the lower portion of the ballhead and, thus, retain the ballhead in the receiving socket. Using a coupler such as that illustrated in the Chambers patent requires a conventional two-step operation in which a first step seats the ball within the socket, and a second subsequent step engages a latching mechanism to latch the seated ball in the socket.
Manual intervention is needed to couple or uncouple the trailer, and the Chambers patent is illustrative of the general approach of requiring the operator to physically actuate a form of latching or locking mechanism after the coupler engages the ball to prevent inadvertent or unwanted uncoupling. Applicants are unaware of any reliable coupler design which eliminates the need for the operator to physically lock the coupler in the latched position.
Two common problems arise from the use of manually operated latching mechanisms which require the operator to lock the mechanism after engaging the coupler with the ballhead. First, operators are known to occasionally forget to engage the locking mechanism. Unfortunately, this oversight is often not noticed until the vehicle and trailer reach a relatively high road speed, and the trailer uncouples. The reason for this is that trailers are typically designed, by the placement of the axle, for balance so that the wheels support the substantial weight of the trailer and the coupler or tongue supports a relatively small portion of the trailer weight. Nevertheless, this relatively small weight at the coupler is usually sufficient to maintain the coupling when traveling at low speeds. At higher speeds, however, even small bumps can cause the trailer to uncouple, having potentially disastrous consequences.
A second problem with manually operated latching mechanisms is that they are often improperly latched. It is important that the receiving socket of the trailer coupler be fully seated over the ballhead before engaging the ball clamp. It is known, however, that occasionally operators--particularly persons that infrequently use and couple trailers--mistakenly engage the manual latch before the receiving socket is fully seated over the ballhead. This is sometimes referred to as false coupling, and the repercussions are the same as if the latching mechanism had not been engaged at all.